very unhappy and left in limbo

I brought airtime for R5 rand yesterday and send only 2 sms. The next thing when I check my airtime balance is R0.00 I then called MTN to try and find out what happened to my airtime, I was told that they could see that I only sent two sms but could not tell me what happened to the rest of the airtime as the system was down, I was told to call after 3 hours I did then. When I called again they told me the same story, I called for the 3rd time and still the system is down. Tried calling this morning and still the system is down. I am so disappointed because now I cant buy airtime as I don't know if it will disappear again and nobody knows what happened to it. This is unacceptable for such a big company like MTN that I have been with for so many years, I cant believe that they would treat their customers like this